Ultra-Wideband (UWB) wireless communication enables data transmission at unprecedented high rates. Video transmission benefits from these high rates because high-definition video formats can now be transmitted at lower compression ratios than previously possible. Prior art systems rely on frame-based or block-based compression schemes, which fall into two broad categories.
To transmit video over a channel with specified capacity, non-scalable rate-control methods employ complicated heuristics to select quantization parameters that compress blocks of video frames so that the average bit rate is close to the channel capacity. However, because instantaneous bit rates may greatly exceed the channel capacity, these methods use large buffers to prevent data loss.
When video is transmitted with scalable rate control, each video frame or block is coded into a scalable (or embedded) bit stream which may be truncated at any point to guarantee that the instantaneous bit rate never exceeds the channel capacity. However, these methods use enough memory to buffer an entire frame or block so that complex, multipass, bit plane-oriented processing can generate a scalable bit stream.
Typically, video rate-control methods apply rate-distortion theory to optimize quality by minimizing distortion for a given rate. In practice, frame-based and block-based video coders use multipass methods or expensive searches, for rate-constrained distortion minimization.
In contrast to frame-based and block-based systems, the proposed line-based rate control adapts video compression on a line-by-line basis to varying system conditions such as buffer status and channel capacity. As wireless video systems move from frame- and block-based to line-based rate control, there is a need in the art for determining the minimal quantization parameters for line-based rate control such that maximal video quality is obtained without buffer overflow, under varying channel capacity.